Numerical investigation of noise-induced resonance in a semiconductor laser with optical feedback

We numerically study the effect of additive Gaussian white noise in the dynamics of a time-delayed feedback system. The system is a semiconductor laser with optical feedback from a distant reflector. For moderate feedback levels the system presents several coexisting attractors, and noise levels above a threshold value induce jumps among these attractors. Based on the residence times probability density, P(I), we show that with increasing noise the dynamics of attractor jumping exhibits a resonant behavior. P(I) presents peaks at multiples of the external-cavity delay time, and the strength of the peaks reaches a maximum value for an optimal level of noise. The results are explained by the interplay of noise and delayed feedback.